In his remarks after Mitt Romney introduced him as his running mate today, Paul Ryan said: “We promise equal opportunity, not equal outcomes.”

We liberals agree that America should offer equal opportunity and not equal outcomes. Conservatives often suggest that we liberals are “levelers” who also want equal outcomes; but that is not true.

So let this race be about which ticket – Obama-Biden or Romney-Ryan – genuinely believes in Ryan’s statement, which I will term “the American promise.”

Let's debate what equal opportunity means.

No one believes it means absolutely equal opportunity. No one, for example, wants to require that all children attend perfectly equal schools. Children with wealthy parents can send their children to excellent private schools and colleges, while other children must depend upon public schools and universities. But if the American promise means anything, it requires that, when necessary, government provide enough assistance so that all children have meaningful opportunities to pursue their goals and realize their aspirations. That requires adequate public schools, affordable public universities, good public libraries, decent nutrition, access to health care, clean air and water, and wholesome communities.

Ayn Rand and her devotees – and today Paul Ryan is Ayn Rand’s most important devotee – talk a lot about liberty. Let this election be about what liberty means. Does it mean merely being free of governmental coercion or does it include having reasonable opportunities to pursue one’s aspirations?

Let us get beyond the rhetoric and have an intelligent, full-throated debate about such things. And as part of the debate, let Paul Ryan explain how Ayn Rand's belief in “the virtue of selfishness” fits with the American promise. It will be interesting.